China is stepping up restrictions on the production, sale and use of single-use plastic products, the state planner said on Sunday, as it seeks to tackle one of the country’s biggest environmental problems.

Vast amounts of untreated plastic waste are buried in landfills or dumped in rivers. The United Nations has identified single-use plastics as one of the world’s biggest environmental challenges.

The National Development and Reform Commission and the Ministry of Ecology and Environment, which issued the new policy, said plastic bags will be banned in all of China’s major cities by the end of 2020 and banned in all cities and towns in 2022. Markets selling fresh produce will be exempt from the ban until 2025.

Other items such as plastic utensils from takeaway food outlets and plastic courier packages will also be phased out.

By end of 2020, the restaurant industry will be banned from using single-use straws. By 2025, towns and cities across China must reduce the consumption of single-use plastic items in the restaurant industry by 30%.

Some regions and sectors will also face restrictions on the production and sale of plastic products, although it is not yet clear which geographical areas.